Problem: $\dfrac{3}{4} + \dfrac{3}{10} = {?}$
Solution: ${\dfrac{3}{4}}$ ${\dfrac{3}{10}}$ $+$ ${\dfrac{3 \times 5}{4 \times 5}}$ ${\dfrac{3 \times 2}{10 \times 2}}$ $+$ ${\dfrac{15}{20}}$ ${\dfrac{6}{20}}$ $+$ $ = \dfrac{{15} + {6}}{20} $ $ = \dfrac{21}{20}$